Method and apparatus for generating binary hologram

ABSTRACT

Provided is a method and apparatus for generating a binary hologram. More particularly, provided is a method and apparatus that may decrease or, alternatively, minimize quality degradation of a binary hologram by employing a silhouette mask of a target object to reduce or, alternatively, minimize background noise occurring around the target object to be reproduced when generating the binary hologram.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the priority benefit of Korean PatentApplication No. 10-2015-0182054 filed on Dec. 18, 2015, and KoreanPatent Application No. 10-2016-0100322 filed on Aug. 5, 2016, in theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference for all purposes.

BACKGROUND

1. Field

One or more example embodiments relate to a method of generating abinary hologram and a binary hologram generation apparatus forperforming the method, and more particularly, to a method and apparatusthat may decrease or, alternatively, minimize background noise occurringafter a binary hologram generation process.

2. Description of Related Art

Recently, with the boost of three-dimensional (3D) imaging industry and3D display industry, research on holography technology, known as a 3Dimaging scheme, has been actively conducted. Here, the holographytechnology may record phase information of an object by the interferencebetween two light waves, “reference wave” and “object wave”. Suchholography technology may have the most excellent characteristics in adepth effect, etc., compared to other 3D imaging methods, and enables auser to observe a 3D image without having a visual fatigue.

Also, thanks to the dramatically developed digital technology andcomputing technology, the holography technology may produce a hologramthrough computer-generated hologram (CGH) technology that generates aninterference pattern between an object wave and a reference wave througha computer simulation, instead of using an optical method.

Accordingly, a hologram generated through a computer may reproduce aholographic 3D image through optical reconstruction using a spatiallight modulator (SLM). Here, in the case of the holographic 3D image, atype of a hologram to be used may vary based on a type of the SLM. Inparticular, a digital micro-mirror display (DMD) uses a hologram havinga binary value (0, 1) based on whether a micro mirror operates or not.However, when the DMD needs to use a 1-bit hologram, a binary hologramhaving a 1-bit value is to be generated from a calculated complex valueor real number value. Accordingly, due to constraints that a binaryhologram also has to use a binary value, a quality degradation may occursimilar to as in a binary image.

Accordingly, there is a need for a method that may decrease or,alternatively, minimize a quality degradation after generating a binaryhologram.

SUMMARY

At least one example embodiment provides a binary hologram generationmethod and apparatus that may employ a silhouette mask of a targetobject during a binarization process to decrease or, alternatively,minimize a quality degradation occurring around the target object whengenerating a binary hologram of the target object to be reproduced.

According to an aspect of at least one example embodiment, there isprovided a method of generating a binary hologram, the method includingreceiving data information used to construct a target object in athree-dimensional (3D) shape to be reproduced as a hologram; generatinga silhouette mask of the target object based on the data information;generating a hologram having a complex value or a real number value inassociation with the target object based on the data information; andbinarizing the hologram having the complex value or the real numbervalue based on the silhouette mask of the target object.

The data information may include depth information and color informationof the target object between which a one-to-one correspondence mappingis established, and the depth information may be quantized to 256 levels(8 bits).

The hologram may be visualized as an image having a resolution of M×Nthat satisfies a spatial resolution of a spatial light modulator (SLM)and represented based on 256 levels (8 bits).

The binarizing may include performing a first quantization process ofallocating 0 or 1 to each of pixels that constitute a plane of thehologram; applying the silhouette mask to the hologram quantized to 0 or1; and performing a second quantization process based on a distancebetween the silhouette mask applied to the quantized hologram and eachpixel of the plane.

The performing of the first quantization process may include allocating0 or 1 to each pixel of the plane based on a threshold thereof.

The threshold may include one of a mean value, a median value, and amid-point value using an absolute value of the complex value or the realnumber value.

The performing of the first quantization process may include allocating0 to a pixel if a value of the corresponding pixel is less than thethreshold; and allocating ‘1’ to a pixel if a value of the correspondingpixel is greater than or equal to the threshold.

The performing of the second quantization process may includedetermining an inverse number value of the distance between thesilhouette mask and each pixel of the plane; and performing the secondquantization process based on the determined inverse number value of thedistance.

The distance between the silhouette mask and each pixel of the plane maybe based on at least one of a horizontal distance and a verticaldistance between the silhouette mask and each pixel of the plane.

According to another aspect of at least one example embodiment, there isprovided a method of generating a binary hologram, the method includingreceiving data information used to construct a target object in a 3Dshape to be reproduced as a hologram; generating a silhouette mask ofthe target object based on the data information; generating a hologramhaving a complex value or a real number value in association with thetarget object based on the data information; applying the silhouettemask of the target object to the hologram having the complex value orthe real number value; determining a distance between the silhouettemask applied to the hologram and each of pixels that constitute a planeof the hologram; and setting a different threshold to each pixel of theplane by applying the determined distance to a threshold set to thehologram.

The binarizing may include allocating 0 or 1 to each pixel value basedon the different threshold set to each pixel of the plane.

According to another aspect of at least one example embodiment, there isprovided an apparatus for generating a binary hologram, the apparatusincluding an information receiver configured to receive data informationused to construct a target object in a 3D shape to be reproduced as ahologram; a silhouette mask generator configured to generate asilhouette mask of the target object based on the data information; ahologram generator configured to generate a hologram having a complexvalue or a real number value in association with the target object basedon the data information; and a binarizer configured to binarize thehologram having the complex value or the real number value based on thesilhouette mask of the target object.

The binarizer may include a first quantizer configured to perform afirst quantization process of allocating 0 or 1 to each of pixels thatconstitute a plane of the hologram; a silhouette mask applier configuredto apply the silhouette mask to the hologram quantized to 0 or 1; and asecond quantizer configured to perform a second quantization processbased on a distance between the silhouette mask applied to the quantizedhologram and each pixel of the plane.

The first quantizer may be further configured to allocate 0 or 1 to eachpixel of the plane based on a threshold thereof.

The first quantizer may be further configured to allocate 0 to a pixelif a value of the corresponding pixel is less than the threshold, and toallocate ‘1’ to a pixel if a value of the corresponding pixel is greaterthan or equal to the threshold.

The second quantizer may be further configured to perform a secondquantization process based on an inverse number value of a distancebetween the silhouette mask and each pixel of the plane.

According to example embodiments, there may be provided a binaryhologram generation method and apparatus that may generate a binaryhologram by employing a silhouette mask of a target object to decrease,or alternatively, minimize a quality degradation occurring around thetarget object through a binarization when generating the binaryhologram, and may decrease or, alternatively, minimize the qualitydegradation occurring due to background noise around the target objectat optical reconstruction.

Additional aspects of example embodiments will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects, features, and advantages of the inventionwill become apparent and more readily appreciated from the followingdescription of example embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a diagram illustrating a configuration of a binary hologramgeneration apparatus according to an example embodiment;

FIG. 2 is a diagram illustrating a configuration of a binary hologramgeneration apparatus according to an example embodiment;

FIG. 3 illustrates examples of data information of a target objectaccording to an example embodiment;

FIG. 4 illustrates an example of a silhouette mask of a target objectaccording to an example embodiment;

FIG. 5 illustrates an example of a hologram having a complex value or areal number value in association with a target object according to anexample embodiment;

FIGS. 6A-6C illustrate an operation of binarizing a hologram accordingto an example embodiment; and

FIG. 7 is a flowchart illustrating a method of generating a binaryhologram according to an example embodiment.

DETAILED DESCRIPTION

Hereinafter, some example embodiments will be described in detail withreference to the accompanying drawings. Regarding the reference numeralsassigned to the elements in the drawings, it should be noted that thesame elements will be designated by the same reference numerals,wherever possible, even though they are shown in different drawings.Also, in the description of embodiments, detailed description ofwell-known related structures or functions will be omitted when it isdeemed that such description will cause ambiguous interpretation of thepresent disclosure.

Hereinafter, example embodiments will be described with reference to theaccompanying drawings.

FIG. 1 is a diagram illustrating a configuration of a binary hologramgeneration apparatus according to an example embodiment.

Referring to FIG. 1, a binary hologram generation apparatus 101 maygenerate a binary hologram 103 of a target object 102 to be reproduced.Here, the binary hologram generation apparatus 101 may generate thebinary hologram 103 by applying a silhouette mask of the target object102 to remove background noise occurring around the target object 102after a process of generating the binary hologram 103. The binaryhologram generation apparatus 101 may decrease or, alternatively,minimize a quality degradation by background noise occurring around thetarget object 102 by generating the binary hologram 103 using thesilhouette mask of the target object 102.

To this end, the binary hologram generation apparatus 101 may receivedata information of the target object 102 to be reproduced as abinarized hologram. The data information of the target object 102 mayinclude color information and depth information of the target object102, which will be further described with reference to FIG. 3. Thetarget object 102 refers to a target to be reproduced as athree-dimensional (3D) image, and may be a model in a 3D shape. Forexample, the target object 102 may include a 3D model that isrepresented in a head shape of a human being, and may include a scene tobe reproduced.

The binary hologram generation apparatus 101 may generate the silhouettemask of the target object 102 based on the received data information ofthe target object 102. That is, the binary hologram generation apparatus101 may generate the silhouette mask corresponding to an externalappearance of the target object 102 based on color information and depthinformation that are included in the data information of the targetobject 102.

The binary hologram generation apparatus 101 may generate a hologramhaving a complex value or a real number value in association with thetarget object 102, based on the data information. Here, a hologram maybe generated by the interference between an object wave reflected froman object, for example, a target to be reproduced and a reference waveincident in a predetermined direction, and may be generated according tocomputer-generated hologram (CGH) technology for generating theinterference pattern between an object wave and a reference wave througha computer simulation. Also, when generating a hologram, a virtual 3Dobject may be regarded as an aggregation of self-emitting point lightsources having the same angular intensity distribution characteristic,which may become an object wave. Accordingly, a digital hologramgeneration method may representatively employ Rayleigh-Sommerfeld (R-S)integral, and may include a Fresnel hologram, Fourier hologram, etc.,based on an approximation method thereof. Here, a method of generating ahologram based on 3D data information may generate a hologram through avariety of methods in addition to the aforementioned methods.

The binary hologram generation apparatus 101 may binarize the hologramusing the silhouette mask of the target object 102. The binary hologramgeneration apparatus 101 may binarize the hologram by performing a firstquantization process and a second quantization process.

In detail, the binary hologram generation apparatus 101 may perform afirst quantization process of allocating 0 or 1 to each of pixels (also,referred to as each pixel of a plane) that constitute a plane of thehologram. The binary hologram generation apparatus 101 may perform thefirst quantization process by changing a value set to each pixel of theplane to 0 or 1. Here, the binary hologram generation apparatus 101 mayallocate 0 or 1 to each pixel of the plane based on a threshold thereof.

The binary hologram generation apparatus 101 may apply the silhouettemask to the hologram quantized to 0 or 1. That is, the binary hologramgeneration apparatus 101 may overlap the silhouette mask generated basedon the external appearance of the target object 102 over the hologramquantized to 0 or 1. That is, the binary hologram generation apparatus101 may apply the silhouette mask of the target object 102 over thequantized hologram so that a shape of the target object 102 to bereproduced may appear in the hologram quantized to 0 or 1. Accordingly,whether each of the pixels that constitute the plane of the hologram ispresent within or outside the silhouette mask may be verified.

The binary hologram generation apparatus 101 may perform the secondquantization process based on a distance between the silhouette maskapplied to the quantized hologram and each of the pixels that constitutethe plane of the quantized hologram present outside the silhouette mask,that is, a mask-to-pixel distance. Through the process, the binaryhologram generation apparatus 101 may generate the binary hologram 103of the target object 102 by binarizing the hologram having the complexvalue or the real number value.

The binary hologram generation apparatus 101 may use the silhouette maskof the target object 102 to reduce or, alternatively, minimizebackground noise of the target object 102 occurring after a hologrambinarization process. The binary hologram generation apparatus 101 maygenerate the binary hologram 103 of which quality degradation occurringafter the hologram binarization process is minimized by binarizing thehologram having the complex value or the real number value using thesilhouette mask of the target object 102.

FIG. 2 is a diagram illustrating a configuration of a binary hologramgeneration apparatus according to an example embodiment.

Referring to FIG. 2, a binary hologram generation apparatus 201 maygenerate a binary hologram 210 of a target object 209 by binarizing ahologram having a complex value or a real number value in associationwith the target object 209 to be reproduced. To this end, the binaryhologram generation apparatus 201 may include an information receiver202, a silhouette mask generator 203, a hologram generator 204, and abinarizer 205.

The information receiver 202 may receive data information used toconstruct the target object 209 in a 3D shape to be reproduced as ahologram. In detail, the information receiver 202 may receive datainformation that includes color information and depth information of thetarget object 209. Here, the color information and the depth informationof the target object 209 may have a one-to-one correspondence mapping.

The silhouette mask generator 203 may generate the silhouette mask ofthe target object 209 based on the data information. That is, thesilhouette mask generator 203 may generate the silhouette mask thatrepresents an external appearance of the target object 209 to bereproduced.

For example, the silhouette mask generator 203 may generate thesilhouette mask that represents the external appearance of the objecttarget 209 based on the data information. Here, the silhouette maskgenerator 203 may set a region of interest (ROI) associated with theexternal appearance of the target object 209, and may generate thesilhouette mask of the target object 209 by separating an areacorresponding to the external appearance of the target object 209 and abackground area from the ROI.

As another example, the silhouette mask generator 203 may generate thesilhouette mask of the target object 209 based on feature points of thetarget object 209. That is, the silhouette mask generator 203 mayextract feature points associated with the external appearance of thetarget object 209 based on color information and depth information ofthe target object 209 that are included in the data information. Indetail, the silhouette mask generator 209 may extract outline featurepoints corresponding to a facial area of the target object 209. Thesilhouette mask generator 203 may generate the silhouette mask from thefacial area of the target object 209 based on the extracted featurepoints. In addition, the silhouette mask generator 203 may generate thesilhouette mask of the target object 209 through various algorithmsbesides the aforementioned methods.

The hologram generator 204 may generate the hologram having the complexvalue or the real number value in association with the target object 209based on data information. Here, the hologram having the complex valueor the real number value may be visualized as an image having aresolution of M×N that satisfies a spatial resolution of a spatial lightmodulator (SLM) and represented based on 256 levels (8 bits).

The binarizer 205 may binarize the hologram having the complex value orthe real number value using the silhouette mask of the target object209. To this end, the binarizer 205 may include a first quantizer 206, amask applier 207, and a second quantizer 208.

The first quantizer 206 may perform a first quantization process ofallocating 0 or 1 to each of pixels that constitute a plane of thehologram. That is, the first quantizer 206 may perform the firstquantization process by changing a value set to each pixel of the planeto 0 or 1.

Here, the first quantizer 206 may calculate a global threshold for eachpixel of the plane in order to perform the first quantization process.Here, the global threshold may be i) one of a mean value, a medianvalue, and a mid-point value using an absolute value of the complexvalue or ii) one of a mean value, a median value, and a mid-point valueusing the real number value. Also, the global threshold may include atleast one value corresponding to each pixel value.

The first quantizer 206 may allocate 0 or 1 to each pixel based on athreshold thereof. In detail, if a value of a pixel is less than thethreshold, the first quantizer 206 may allocate 0 to the correspondingpixel. Also, if a value of a pixel is greater than or equal to thethreshold, the first quantizer 206 may allocate 1 to the correspondingpixel.

As described above, the first quantizer 206 may perform the firstquantization process on the hologram having the complex value or thereal number value by changing, to 0 or 1 based on the threshold, a valueset to each of the pixels that constitute the plane of the hologramhaving the complex value or the real number value.

Although it is described that the first quantization process isperformed using the global threshold, it is provided as an example only.The first quantization process may be performed using an iterativecalculation method and the like, instead of using the global threshold.

The mask applier 207 may apply the silhouette mask to the hologramquantized to 0 or 1. The mask applier 207 may apply the silhouette maskof the target object 102 to the quantized hologram so that a shape ofthe target object 102 to be reproduced may appear in the hologramquantized to 0 or 1. Accordingly, whether each of the pixels thatconstitute the plane of the hologram is present within or outside thesilhouette mask may be verified.

The second quantizer 208 may perform a second quantization process basedon a distance between the silhouette mask applied to the quantizedhologram and each of the pixels that constitute the plane of thequantized hologram present outside the silhouette mask, that is, amask-to-pixel distance. Here, the distance between the silhouette maskand each pixel of the plane may be determined based on at least one of ahorizontal distance and a vertical distance from the silhouette mask.

In detail, the second quantizer 208 may calculate a horizontal/verticaldistance between each pixel of the plane and a most proximate pixelpresent in the silhouette mask, for example, a facial area of the targetobject 209. The second quantizer 208 may acquire an inverse number valueof the calculated distance (or apply a weight to the calculateddistance) and may multiply the inverse number value (or the distance towhich the weight is applied) by a first quantization value. Accordingly,a pixel to which 0 is allocated may be maintained to have 0 as is, and avalue having a decimal point may be allocated to a pixel to which 1 isallocated. The second quantizer 208 may calculate a final result that apixel has a value of 0 or 1 by rounding off the value having the decimalpoint or by applying thresholding based on a specific value, forexample, 0.2.

According to example embodiments, the second quantization process may beperformed by applying thresholding based on a specific value, forexample, 4, using a weight or a distance between pixels, as well as aninverse number value.

The second quantizer 208 may calculate the distance using a variety ofmethods, such as Euclidean distance, Hausdorff distance, a squaredistance of Euclidean distance, etc.

The second quantizer 208 may determine an inverse number value of thedistance between the silhouette mask and each pixel of the plane. Thesecond quantizer 208 may perform the second quantization process on thehologram to which the first quantization process is performed based onthe determined inverse number value of the distance.

That is, if a distance from the silhouette mask to a pixel thatconstitutes a plane of the quantized hologram is relatively far, it mayindicate that the corresponding pixel is highly likely to act asbackground noise rather than acting as significant data associated withthe target object 209. The silhouette mask refers to informationindicating the external appearance of the target object 209. If adistance from the silhouette mask to a pixel is relatively proximate, itmay indicate that the corresponding pixel is highly likely to besignificant data.

Accordingly, the second quantizer 208 may filter out data associatedwith background noise occurring after the hologram binarization processby performing the second quantization process based on the distancebetween the silhouette mask and each pixel.

The binarizer 205 may generate the binary hologram 210 of the targetobject 209 by performing the aforementioned process.

Although not illustrated in FIG. 2, the binary hologram generationapparatus 201 may binarize the hologram having the complex value or thereal number value through the following process, instead of performingthe first quantization process and the second quantization process.

In detail, the binary hologram generation apparatus 201 may receive datainformation used to configure the target object 209 in the 3D shape tobe reproduced as a hologram and may generate the silhouette mask of thetarget object 209 based on the data information.

The binary hologram generation apparatus 201 may generate the hologramhaving the complex value or the real number value in association withthe target object 209 based on the data information. The binary hologramgeneration apparatus 201 may apply the silhouette mask of the targetobject 209 to the hologram having the complex value or the real numbervalue.

The binary hologram generation apparatus 201 may determine a distancebetween the silhouette mask applied to the hologram and each of thepixels that constitute the hologram. The binary hologram generationapparatus 201 may set a different threshold to each pixel of the planeby applying the determined distance to a threshold set to the hologram.That is, a pixel relatively far from the silhouette mask may be set tohave a relatively high threshold. The binary hologram generationapparatus 201 may binarize the hologram in which different thresholdsare set to pixels.

FIG. 3 illustrates examples of data information of a target objectaccording to an example embodiment.

Referring to FIG. 3, a binary hologram generation apparatus may receivedata information used to construct the target object in a 3D shape.Here, the data information used to construct the target object in the 3Dshape may include color information and depth or displacementinformation associated with the target object and a scene. That is, CGHtechnology generally used to generate a hologram may use colorinformation, for example, red, green, blue (RGB), and 3D spatialinformation, for example, X, Y, and Z, associated with the target objector the scene to be reproduced, in order to generate the hologram througha computer simulation. Accordingly, the binary hologram generationapparatus may receive color information and depth information of thetarget object as data information used to construct the target object inthe 3D shape.

Also, the data information may be a model having a surface and may be awireframe model as shown in FIG. 3 and may include color information anddepth information thereof. Without being limited thereto, the exampleembodiments may be configured in various shapes. Color information anddepth information have a one-to-one correspondence mapping, and thedepth information is quantized to 256 levels (8 bits).

FIG. 4 illustrates an example of a silhouette mask of a target objectaccording to an example embodiment.

Referring to FIG. 4, a binary hologram generation apparatus may generatethe silhouette mask of the target object based on data information. Thatis, the binary hologram generation apparatus may generate the silhouettemask corresponding to the external appearance of the target object basedon color information and depth information that are included in datainformation of the target object.

FIG. 5 illustrates an example of a hologram having a complex value or areal number value in association with a target object according to anexample embodiment.

Referring to FIG. 5, a binary hologram generation apparatus may generatethe hologram having the complex value or the real number value inassociation with the target object 102 of FIG. 2 based on datainformation. Here, the hologram of FIG. 5 is represented as an 8-bit(256 levels) image based on an absolute value of the complex value forvisualization. The hologram may be represented as an image having aresolution of M×N that satisfies a spatial resolution of an SLM and maybe represented as data having a complex value or a real number value ina form of M×N.

FIG. 6 illustrates an operation of binarizing a hologram according to anexample embodiment.

Referring to (a) of FIG. 6, a binary hologram generation apparatus maygenerate a hologram capable of representing a hologram having anabsolute value of a complex value as an 8-bit (256-level) image. Thatis, the binary hologram generation apparatus may generate a hologramhaving a complex value or a real number value from data information.Here, the hologram may actually have an absolute value of the complexvalue rather than 8-bit image which is just for the visualization.

The binary hologram generation apparatus may perform a firstquantization process of allocating 0 or 1 to each of pixels thatconstitute a plane of the hologram. In detail, the binary hologramgeneration apparatus may perform the first quantization process on thehologram represented as the absolute value of the complex value or thereal number value, based on a medium value (=(MAX+MIN)/2) with respectto the range of the real number value or the absolute value of thecomplex value.

(b) of FIG. 6 may show a result of performing the first quantizationprocess. Referring to (b) of FIG. 6, lines connected to the targetobject may appear around the target object after binarization, which mayact as background noise in actual optical reconstruction.

According to example embodiments, it is possible to enhance the qualityof a holographic 3D reconstruction image by removing such backgroundnoise. To this end, the binary hologram generation apparatus may performa second quantization process using the silhouette mask of the targetobject and may filter outportions corresponding to the background noise.Accordingly, it is possible to reduce a quality degradation by thebackground noise occurring around the target object as shown in (c) ofFIG. 6.

FIG. 7 is a flowchart illustrating a method of generating a binaryhologram according to an example embodiment.

In operation 701, a binary hologram generation apparatus may receivedata information used to construct a target object in a 3D shape to bereproduced as a hologram. Here, the data information may include colorinformation and depth information of the target object between which aone-to-one correspondence mapping is established. The depth informationmay be quantized to 256 levels (8 bits).

In operation 702, the binary hologram generation apparatus may generatea silhouette mask of the target object based on the data information.

In operation 703, the binary hologram generation apparatus may generatea hologram having a complex value or a real number value in associationwith the target object based on the data information. Here, the hologramhaving the complex value or the real number value may be represented asa 256 levels (8 bits) image for the visualization having a resolution ofM×N that satisfies a spatial resolution of an SLM.

In operation 704, the binary hologram generation apparatus may binarizethe hologram having the complex value or the real number value using thesilhouette mask of the target object. In detail, the binary hologramgeneration apparatus may perform a first quantization process ofallocating 0 or 1 to each of pixels that constitute a plane of thehologram. The binary hologram generation apparatus may allocate 0 or 1to each pixel based on a threshold thereof. Here, the threshold mayinclude at least i) one of a mean value, a median value, and a mid-pointvalue using an absolute value of a complex value or ii) one of a meanvalue, a median value, and a mid-point value using a real number value.

The binary hologram generation apparatus may allocate 0 to a pixel if avalue of the corresponding pixel is less than the threshold, or mayallocate 1 to a pixel if a value of the corresponding pixel is greaterthan or equal to the threshold.

The binary hologram generation apparatus may apply the silhouette maskto the hologram quantized to 0 or 1.

The binary hologram generation apparatus may perform a secondquantization process based on a distance between the silhouette maskapplied to the quantized hologram and each pixel of the plane. Thebinary hologram generation apparatus may determine an inverse numbervalue of the distance between the silhouette mask and each pixel of theplane. The binary hologram generation apparatus may perform the secondquantization process using the determined inverse number value of thedistance.

The components described in the exemplary embodiments of the presentinvention may be achieved by hardware components including at least oneDSP (Digital Signal Processor), a processor, a controller, an ASIC(Application Specific Integrated Circuit), a programmable logic elementsuch as an FPGA (Field Programmable Gate Array), other electronicdevices, and combinations thereof. At least some of the functions or theprocesses described in the exemplary embodiments of the presentinvention may be achieved by software, and the software may be recordedon a recording medium. The components, the functions, and the processesdescribed in the exemplary embodiments of the present invention may beachieved by a combination of hardware and software.

The processing device described herein may be implemented using hardwarecomponents, software components, and/or a combination thereof. Forexample, the processing device and the component described herein may beimplemented using one or more general-purpose or special purposecomputers, such as, for example, a processor, a controller and anarithmetic logic unit (ALU), a digital signal processor, amicrocomputer, a field programmable gate array (FPGA), a programmablelogic unit (PLU), a microprocessor, or any other device capable ofresponding to and executing instructions in a defined manner. Theprocessing device may run an operating system (OS) and one or moresoftware applications that run on the OS. The processing device also mayaccess, store, manipulate, process, and create data in response toexecution of the software. For purpose of simplicity, the description ofa processing device is used as singular; however, one skilled in the artwill be appreciated that a processing device may include multipleprocessing elements and/or multiple types of processing elements. Forexample, a processing device may include multiple processors or aprocessor and a controller. In addition, different processingconfigurations are possible, such as parallel processors.

The methods according to the above-described example embodiments may berecorded in non-transitory computer-readable media including programinstructions to implement various operations of the above-describedexample embodiments. The media may also include, alone or in combinationwith the program instructions, data files, data structures, and thelike. The program instructions recorded on the media may be thosespecially designed and constructed for the purposes of exampleembodiments, or they may be of the kind well-known and available tothose having skill in the computer software arts. Examples ofnon-transitory computer-readable media include magnetic media such ashard disks, floppy disks, and magnetic tape; optical media such asCD-ROM discs, DVDs, and/or Blue-ray discs; magneto-optical media such asoptical discs; and hardware devices that are specially configured tostore and perform program instructions, such as read-only memory (ROM),random access memory (RAM), flash memory (e.g., USB flash drives, memorycards, memory sticks, etc.), and the like. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The above-described devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described example embodiments, or viceversa.

A number of example embodiments have been described above. Nevertheless,it should be understood that various modifications may be made to theseexample embodiments. For example, suitable results may be achieved ifthe described techniques are performed in a different order and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Accordingly, other implementations arewithin the scope of the following claims.

What is claimed is:
 1. A method of generating a binary hologram, themethod comprising: receiving data information used to construct a targetobject in a three-dimensional (3D) shape to be reproduced as a hologram;generating a silhouette mask of the target object based on the datainformation; generating a hologram having a complex value or a realnumber value in association with the target object based on the datainformation; and binarizing the hologram by: performing a firstquantization process of allocating 0 or 1 to each pixel that constitutesa plane of the hologram; applying the silhouette mask to the hologramquantized to 0 or 1; and performing a second quantization process basedon a distance between the silhouette mask applied to the quantizedhologram and each pixel of the plane that is outside the silhouettemask, and displaying the hologram on a spatial light modulator (SLM). 2.The method of claim 1, wherein the data information includes depthinformation and color information of the target object between which aone-to-one correspondence mapping is established, and the depthinformation is quantized to 256 levels (8 bits).
 3. The method of claim1, wherein the spatial light modulator (SLM) has a resolution of M×Nthat has 256 levels (8 bits).
 4. The method of claim 1, whereinperforming the first quantization process comprises allocating 0 or 1 toeach pixel of the plane based on a threshold thereof.
 5. The method ofclaim 4, wherein the threshold includes at least one of a mean value, amedian value, and a mid-point value using an absolute value of thecomplex value or one of a mean value, a median value, and a mid-pointvalue using the real number value.
 6. The method of claim 4, whereinperforming the first quantization process comprises: allocating 0 to apixel if a value of the corresponding pixel is less than the threshold;and allocating 1 to a pixel if a value of the corresponding pixel isgreater than or equal to the threshold.
 7. The method of claim 1,wherein performing the second quantization process comprises:determining an inverse number value of the distance between thesilhouette mask and each pixel of the plane; and performing the secondquantization process based on the determined inverse number value of thedistance.
 8. The method of claim 7, wherein the distance between thesilhouette mask and each pixel of the plane is based on at least one ofa horizontal distance and a vertical distance between the silhouettemask and each pixel of the plane.
 9. A method of generating a binaryhologram, the method comprising: receiving data information used toconstruct a target object in a three-dimensional (3D) shape to bereproduced as a hologram; generating a silhouette mask of the targetobject based on the data information; generating a hologram having acomplex value or a real number value in association with the targetobject based on the data information; applying the silhouette mask ofthe target object to the hologram having the complex value or the realnumber value; determining a distance between the silhouette mask appliedto the hologram and each pixel that constitutes a plane of the hologram;setting a different threshold to each pixel of the plane outside of thesilhouette mask by applying the determined distance to a threshold setto the hologram; binarizing all pixels in the hologram by using thedifferent threshold; and displaying the hologram on a spatial lightmodulator (SLM).
 10. The method of claim 9, wherein the binarizingcomprises: allocating 0 or 1 to each pixel value based on the differentthreshold set to each pixel of the plane.
 11. An apparatus forgenerating a binary hologram, the apparatus comprising: an informationreceiver configured to receive data information used to construct atarget object in a three-dimensional (3D) shape to be reproduced as ahologram; a silhouette mask generator configured to generate asilhouette mask of the target object based on the data information; ahologram generator configured to generate a hologram having a complexvalue or a real number value in association with the target object basedon the data information; and a binarizer configured to binarize thehologram, wherein the binarizer comprises: a first quantizer configuredto perform a first quantization process of allocating 0 or 1 to each ofpixels that constitute a plane of the hologram; a silhouette maskapplier configured to apply the silhouette mask to the hologramquantized to 0 or 1; and a second quantizer configured to perform asecond quantization process based on a distance between the silhouettemask applied to the quantized hologram and each pixel outside thesilhouette mask.
 12. The apparatus of claim 11, wherein the firstquantizer is further configured to allocate 0 or 1 to each pixel of theplane based on a threshold thereof.
 13. The apparatus of claim 12,wherein the first quantizer is further configured to allocate 0 to apixel if a value of the corresponding pixel is less than the threshold,and to allocate ‘1’ to a pixel if a value of the corresponding pixel isgreater than or equal to the threshold.
 14. The apparatus of claim 11,wherein the second quantization process is based on an inverse numbervalue of a distance between the silhouette mask and each pixel of theplane that is outside the silhouette mask.